Tubular sets are commonly used for conveying blood between a patient and extracorporeal blood treatment apparatus such as dialyzers, blood oxygenators, and similar devices. In the setup of these devices, they must be initially filled with a physiological solution such as normal saline solution before blood is introduced into the sets and extracorporeal treatment apparatus.
Separate or attached priming sets are used in the prior art to deliver such solutions to the fluid pathways of extracorporeal tube sets and the blood processing devices before, during, and after a medical procedure such as hemodialysis. Before the procedure, saline solution must be used to prime the set""s fluid pathway, displacing all air. During dialysis, saline solution may have to be rapidly added via the set if the patient suffers hypotension. Also, saline solution may be used as a diluent in drug administration which is directly infused into the extracorporeal blood pathway. Then, at the end of dialysis, saline solution is added to the set to displace all blood back to the patient.
Priming sets are basically simplified versions of the conventional i.v. administration sets used in infusion therapy.
A dialysis set comprises a tubular structure having one end connected to a patient connector and the other end connected to the extracorporeal treatment device. Arterial dialysis sets receive blood from the patient and convey it to the extracorporeal device. Venous sets receive blood from the extracorporeal device and convey it back to the patient.
Such a prior art dialysis extracorporeal treatment system comprises an arterial set and a venous set, both of which are connected to a dialyzer. The arterial set also carries a branching tube, called a saline administration branch line, typically terminating with a luer lock connector for connection with an end of the priming set. Thus, the priming set connects with the saline administration branch line of the arterial set, and saline solution may pass in one step upstream in the arterial set to the patient connector end, to fill that area. Then, in another step, clamps are closed and opened to allow saline to pass downstream through the rest of the set, to prime the rest of the entire system.
As another option in the prior art, the priming set, reversibly connected to a bag of physiological solution, is directly connected to the patient connector of the arterial set. Then, the saline can flow in a single step through the entire system of the arterial set, the dialyzer, and the venous set, to prime it. Following this, one must disconnect the patient connector and priming set, and connect the connector of the priming set to the saline administration branch line, since saline solution will be subsequently needed during the dialysis process.
Since connection of the patient connector with the patient is essentially the last step to be performed after priming and before the initiation of the hemodialysis, the wet patient connector in this circumstance may lie around in an exposed manner, waiting for the final priming steps to be performed, particularly the connection of the priming set to the saline administration branch line, and other final steps. This is undesirable, since it leaves the patient connector both wet from its prior connection, and exposed to the air, which invites contamination.
Also, in the prior art, the use of a separate, separable priming set is generally required to enable the multiple connections and disconnections which are commonly used. However, this causes extra expense in connectors, clamps, sterility protectors, and assembly and packaging.
Further in the prior art, a branching injection site is generally provided to the priming set, which becomes a way that drugs and supplemental fluids may be administered to the system. However, an injection site uses a hypodermic needle to obtain connection through it. The flow through such a needle, and also through valved ports, blunt, hollow probes, and the like used as substitutes for needles, is low because needles and the like are constricted, and thus have low flow rates. The flow is particularly not sufficient for high flow needs such as hypotensive fluid replacement or efficient priming/rinse back of the blood line set. Likewise, valved ports have this disadvantage, and also they are much more expensive than injection sites and needles.
Also, in the circumstance where priming is performed directly through the saline administration branch lines of conventional arterial sets, the retrograde flow of fluid back to the arterial patient connector adds time-consuming connections and clamping.
By this invention, a simplification of the priming process is achieved. The system may be primed in a single step from the patient connector, which is advantageous, and the patient connector may simultaneously be protected from contamination until it is fully time to switch the patient connector to engage the blood system of the patient, to effect the extracorporeal blood treatment process. Where in the prior art two connections after priming must be made, one with the patient connector, and the other with the priming set connector and the saline administration branch line of the set, only one connection after priming has to be made in this invention, that of the patient connector. Also, an extra connector becomes available in accordance with this invention which is a higher flow luer connector, rather than a restricted flow needle or an expensive substitute, so that in the event of the urgent need for high flow fluid administration into the set the access is available.
In accordance with this invention, a method is provided of priming an extracorporeal blood set such as a dialysis set, typically connected to an entire dialysis flow system, to fill it with physiological solution. The set comprises tubing having a patient connector on one end thereof, and a branch tube in connection with a source of the physiological solution. The branch tube connects with the blood set between ends of the blood set.
By this invention, the branch tube connects in branching relation with a second connector, for example by using further branch tubing. The second connector is capable of sealing connection with the patient connector. Preferably, each of the patient connector and the second connector has a minimum flow-through bore diameter of at least about two millimeters, which is substantially larger than the bore diameter of needles which are used with injection sites in conventional medical sets. Thus, a relatively high flow rate is possible through these connectors.
Various known connectors exhibit a minimum flow-through bore diameter of at least two millimeters, i.e. there is no constriction of the fluid flow path through the connector of less than two millimeters diameter. The most common are the luer or luer lock connectors, which are preferably used in this invention, and are commonly used throughout the medical field. However, any other connector which fits the requirements and has a flow-through bore diameter of at least two millimeters may be used, for example, screw connectors, bayonet connectors with abutting tubular ends, connectors similar to the Sarns Quick Click connector, clam shell connectors for abutting flanged-end tubing together, and the like. What is excluded are normal medical needle type connectors, certain valved ports which fail to have an adequate flow path diameter, blunt, hollow probes that extend through slit, elastomeric diaphragms, and the like, unless they are somehow designed to have a flow path which is at least two millimeters in diameter throughout its length.
Thus, the method of this invention comprises the steps of: connecting the patient connector and the second connector to form a closed loop of tubing. One then passes the solution from its source in flow through the branch tube and the branching second connector, to fill them and the set tubing with the solution. One then disconnects the patient connector for subsequent connection with a vascular system of a patient. This subsequent connection can be immediate, so that the patient connector is not subject to contamination by spending time exposed to the air. Typically, the patient connector is a conventional male luer lock connector, while the second connector is a conventional female luer lock connector.
It is preferred to practice the method with the further step of blocking (occluding) flow through the branch tube at a first point, which is positioned on the branch tubing between the further branch tubing (branching second connector) and the set tubing. The effect of this is to temporarily cause all of the solution flow from the solution source to pass through the branching second connector, and through the patient connector, and then through the set tubing from the end thereof, so that the priming of the entire system can proceed from one end to the other without any need for a less desirable retrograde flow step.
After this, one then can block or occlude flow through the second connector, and one can simultaneously open flow through the first point in the first branch tube, typically after the set tubing is filled with the solution. Thus, saline flow can now pass directly to the set through the first branch tube if and when needed.
During the extracorporeal blood treatment procedure, one can subsequently connect a third connector, typically a luer connector, to the second connector of the further branch tubing. This third connector typically also has a minimum flow-through bore diameter of at least two millimeters, and can communicate with another source of physiological solution, for example, a drug-containing solution for medicating the patient directly through the set, or added saline in the event of a hypotensive episode. Since the connection of the second and third connectors is preferably a luer connection or the equivalent, rather than a connection through a needle-penetrable injection site or equivalent structures, a much greater flow of solution is available to the patient, which may be lifesaving in the event of a hypotensive episode. Typical branched injection sites which use a needle, or a corresponding, blunt tube, exhibit constricted flow characteristics compared with luer connector systems, since the needle or blunt equivalent must be thin enough to sealingly penetrate through a resilient wall of some kind in an injection site. Thus, significant improvements are achieved by providing the second connector, which is in branching connection with the first branch tubing, providing added capacity for high flow fluid administration to the patient through the set in the event of an emergency, for example a flow of at least 300 ml. per min.
At the end of the extracorporeal blood procedure, one may perform the step of subsequently reconnecting the patient connector and the second connector. More physiological solution may then be passed from the source of solution in flow through the branch tube and further branch tubing, to flush the set tubing with said solution beginning at the patient connector end, through the entire length of the set tubing, and also typically including the dialyzer or other extracorporeal treatment device and the venous set tubing as well.
Thus, the change from the prior art, which comprises the addition of further branch tubing or the like and a second connector as a substitute for a branching injection site of the prior art, provides the above significant opportunities and advantages. By this invention, infusions through the saline administration branch of blood sets greater flow capacities, when compared with injection sites and needles, and their blunt equivalents and valved female connectors. Such high flow infusions are particularly necessary in emergency situations, and may be lifesaving. Also blood line priming of the arterial set may be accomplished without removing the priming set from sterile connection with the blood line.
In a preferred embodiment, the priming set may be integrally attached to the blood line so that the user does not have to make any connection there. Such an integral connection results in decreased parts, allowing significant cost savings. Similarly, blood line rinseback may take place without removing the priming set from its sterile connection with the blood line.